Virus-like particles (VLPs), formed by self-assembly of viral envelop or capsid proteins, resemble viruses, from which the envelop/capsid proteins derive, but lack viral nucleic acids. Like viruses, they are highly immunogenic; unlike viruses, they are not infectious. Given these two features, VLPs are excellent vaccine candidates. They also have the potential for use in drug delivery due to their capacity to encapsulate a drug during assembly.
VLPs can be prepared by conventional recombinant technology. More specifically, one can express viral envelop/capsid proteins in a cell and then assemble the proteins to form particles. E. coli is commonly used as a host for expressing recombinant proteins. However, they are not suitable for producing VLPs as envelop/capsid proteins expressed therein are usually water insoluble.